Neurodegenerative diseases, such as Guillain-Barre syndrome, Huntington's disease and amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS) and Parkinson's Disease (PD) and injuries caused by stoke, atherosclerosis, traumatic injury from accident, and the like, afflict patients with a reduced ability of movement. Parkinson's Disease is a progressive neurodegenerative disease that causes affected individuals to move slowly and make small movements. Subjects with Parkinson's Disease display tremor, rigidity, bradykinesia and postural instability. Without the use of exteroceptive (visual or auditory) input, subjects with PD make hypometric movements (Flowers, Brain, 99:269-310, 1976, Klockgether & Dichgans, Mov. Disord., 9:48-56, 1987) but motor performance improves with auditory or visual cues (Georgiou et al, Brain, 116:1575-78,1993).
The gait in subjects with PD can be described as shuffling, with short hesitant steps that are sometimes quick (festinating). Subjects with PD have difficulty initiating their gait and walk stiffly with limited arm swing. Postural instability is usually a relatively late symptom of the disease and one that is not amenable to current medical or surgical therapy (Koller et al, Clin. Neuropharmacol, 12:98-105, 1989), although some improvement in balance has been reported with bilateral subthalamic stimulators (Bejjani et al., Jour. Neural. Neurosurg. Psych. 68(5):595-600, 2000). Subjects with PD experiencing postural instability are at increased risk of falls resulting in traumatic injuries and are usually dependent on the use of assistive devices such as walkers. In one survey, subjects with PD had a yearly incidence of broken bones of 35.6% of which ⅓ were hip fractures (Pressley et al., Neurology, 60(1):87-93, 2003). Following hip fractures, the gait worsens and 21.9% may be fully unable to walk (Gialanella, Minerva Med., 92(3):11-6, 2001). In addition, freezing and gait hesitation usually occur relatively late in the disease and can be quite debilitating even when the other symptoms of the disease are well-treated medically.
Although subjects with PD are routinely sent for physical therapy to address their gait problems, the efficacy is not well documented. Furthermore, the methods used vary from center to center and have not been subjected to rigorous scientific investigation. Weight-supported treadmill training, a technique in which the subject walks on a treadmill with partial body weight support through an overhead harness as well as a pelvic belt has been found to improve gait stride length and speed in persons with strokes (Miyai et al., Arch. Phys. Med. Rehabil. 81:849-52, 2000) and these benefits may be long-lasting (Miyai et al., Arch. Phys. Med. Rehabil., 83:1370-3, 2002). The mechanism for the improvement is unknown. A portion of the improvement with treadmill training in PD may be due to aerobic conditioning since that seems to be a factor when applied to stroke patients (Macko et al. Stroke, 28:326-330, 1997; Macko et al, Arch. Phys. Med. Rehab., 82(7):879-884, 2001). In this training in subjects with PD, the weight support may be a factor (Visintin et al, Stroke, 29:1122-28, 1998) in the improvement aside from any improvements resulting from more efficient energy expenditure. Frenkel-Toledo et al. (Movement Disorders 20(9)11109-1114, 2005) suggest that the treadmill itself may be acting as an external cue to enhance the rhythmicity of the gait of the subject with PD, but did not demonstrate any stride length improvements.
It is a common observation that subjects with PD may undergo severe “freezing” when attempting to go through doorways but may have little trouble going up stairs or when there is a repeated pattern on the floor. These visual stimuli can have large effects on a subject's gait. There is a commercially-available cane (STEPOVER WAND®) that employs a red wire as a visual stimulus or a visual aid for subjects experiencing freezing. With this device, subjects are explicitly using visual input to help improve the magnitude of their steps. It is well accepted that visual stimuli may improve gait by alleviating freezing, and in fact, there are improvements in gait in subjects with PD with visual and auditory cueing (Suteerawattananon et al, J. Neurol. Sci., 219:63-69, 2004). However, the improvements with auditory cueing (using a metronome) were in cadence rather than stride length (Suteerawattananon et al., Ibid, 2004).
The use of the term “gait improvement,” as used herein, means the alleviation of freezing and hesitation.
The short steps that subjects with PD take are one form of the hypometria they experience, and this is also present during movements of the upper extremities. With visual feedback, subjects are able to make larger limb movements, and the deficit may be due to a sensory-motor mismatch (Demerci et al. Ann. Neurol., 41:781-788, 1997). That is, the kinesthetic signal may be “felt” as indicating the subject has made an adequately-sized movement even though he has not. Subjects with PD perceive distances to be shorter than control subjects when they use kinesthesia rather than vision. Subjects with PD often feel they are speaking at a normal volume even though they may be severely hypophonic (Marsden, Neurology, 32:514-539, 1982), but when they are coerced into speaking louder they feel as if they are shouting (Ramig et al, J. Med. Speech Lang. Pathol, 2:191-209, 1994). Apparently during both limb movements and speech, subjects with PD have a feeling of performing well and do not attempt to make corrections because they do not feel any discrepancy between their motor intention and performance (motor output) as long as there is no exteroceptive feedback. Based on these ideas, improvements in speech have been achieved (the Lee Silverman Voice Treatment program). The focus is on producing a louder volume and this results in improvements in articulation as well (Ramig, Intelligibility in Speech Disorders: Theory, Measurement and Management, John Benjamins Pub. Co., R. Kent, ed., Amsterdam, 1992) even though articulation is not stressed during the therapy. These ideas have not been applied to physical therapies for gait.
U.S. Pat. No. 6,704,603 B1 and divisional U.S. Publication no. 2004/0133249 A1 describe a method of adaptive stimulation and an adaptive stimulator product. The '603 patent describes a control unit and method to aid in the relief of symptoms of Parkinson's disease. The device disclosed electrically stimulates a subject's muscles at a set rhythm to stimulate better movement or uses a signal to tell the subject when to take a step. Stride lengthening is not disclosed.
Since subjects with neurodegenerative disease have a greatly increased risk of suffering traumatic injuries as a result of postural instability, intervention with physical therapies and the use of assistive devices, such as canes and walkers, may be helpful in preventing these falls. Various experimental therapy methods including Body Weight Supported Treadmill Training (Miyai et al., Ibid, 2000, 2002), and visual and auditory cueing (Suteerawattananon et al, Ibid, 2004) have demonstrated some improvement in gait parameters. However, there are no standardized physical therapeutic modalities that lead to improvement in gait or postural stability. There is a need in the art for improving the gait stride length, gait shape, and gait pace of a subject, as well as improving general postural stability in subjects with neurodegenerative disease.
Subjects recovering from surgeries to the lower body, such as total hip replacement, total knee replacement, arthroscopic surgery and prosthetic device implantation as well as subjects recovering from traumatic injuries often exhibit less-than-ideal gaits. That is, the gait of the patient consists of a short stride length, a flat-footed shuffling motion, an unstable step that wavers laterally from the intended stepping direction or combinations thereof. Current physical therapy applied to subjects recovering from these afflictions includes practice of proper walking form and range-of-motion exercises. However, proper performance of the exercises is only ensured when a physical therapist or attending clinician is present to guide the subject. There is a need for improving the range-of-motion, gait stride length, gait shape and gait pace of a subject through guided therapy even in the absence of an attending health care provider.
Subjects, both human and animal, with aesthetic or athletic performance objectives relating to stride and gait characteristic such as optimized stride length, gait shape, cadence and the like can benefit from real-time feedback of their gait characteristics. Human performers and athletes have to rely on reviewing video of their gait after their training session to determine how they must alter their gait in the next training session to more closely reflect desired gait characteristics. Animals that are desired to have certain aesthetic or athletic performance objectives relating to their gait must rely on human trainers to provide feedback of the adequacy of their gait characteristics during the training session. There is a need for real-time feedback to subjects of the adequacy of their gait characteristics in meeting desired gait characteristics without the use of a human trainer.